switch i % 2 {
		case 0:
			blocs = append(blocs, Bloc(blockn(i),
				If("p", blockn(i+1), blockn(i+2))))
		case 1:
			blocs = append(blocs, Bloc(blockn(i),
				If("p", blockn(i+1), blockn(i-1))))
		}
	}

	blocs = append(blocs,
		Bloc(blockn(size), Goto("exit")),
		Bloc("exit", Exit("mem")),
	)

	return blocs
}

// genManyPred creates an array of blocks where 1/3rd have a successor of the

		}
	}
}

// A block tracks label declarations in a block and its enclosing blocks.
type block struct {
	parent *block                         // enclosing block
	lstmt  *syntax.LabeledStmt            // labeled statement to which this block belongs, or nil
	labels map[string]*syntax.LabeledStmt // allocated lazily
}

// insert records a new label declaration for the current block.

					bb := s.Block()
					if ln.b2l[b.ID] == nil && ln.b2l[bb.ID] != nil && bb != ln.b2l[bb.ID].header {
						f.Fatalf("block %s not in loop branches to non-header block %s in loop", b.String(), bb.String())
					}
					if ln.b2l[b.ID] != nil && ln.b2l[bb.ID] != nil && bb != ln.b2l[bb.ID].header && !ln.b2l[b.ID].isWithinOrEq(ln.b2l[bb.ID]) {
						f.Fatalf("block %s in loop branches to non-header block %s in non-containing loop", b.String(), bb.String())

// Compile modifies f so that on return:
//   - all Values in f map to 0 or 1 assembly instructions of the target architecture
//   - the order of f.Blocks is the order to emit the Blocks
//   - the order of b.Values is the order to emit the Values in each Block
//   - f has a non-nil regAlloc field
func Compile(f *Func) {
	// TODO: debugging - set flags to control verbosity of compiler,
	// which phases to dump IR before/after, etc.

	// inBlockUses records whether a value is used in the block
	// in which it lives. (block control values don't count as uses.)
	inBlockUses := f.Cache.allocBoolSlice(f.NumValues())
	defer f.Cache.freeBoolSlice(inBlockUses)
	if f.Config.optimize {
		for _, b := range f.Blocks {
			for _, v := range b.Values {
				for _, a := range v.Args {
					if a.Block == b {
						inBlockUses[a.ID] = true
					}
				}
			}

// a task to be executed without any other concurrent tasks.
const exclusive = -1

// Add blocks until the sequencer has enough weight to spare, then adds f as a
// task to be executed concurrently.
//
// If the weight is either negative or larger than the sequencer's maximum
// weight, Add blocks until all other tasks have completed, then the task
// executes exclusively (blocking all other calls to Add until it completes).

					sa.IsExtended()[0] = 1
				}
				return sp
			}
			sp2 := formatSPD(spd, blk.GNU().Sparse())
			for len(sp2) > 0 {
				var spHdr block
				sp2 = formatSPD(sp2, spHdr.Sparse())
				spb = append(spb, spHdr[:]...)
			}

			// Update size fields in the header block.
			realSize := hdr.Size
			hdr.Size = 0 // Encoded size; does not account for encoded sparse map
			for _, s := range spd {
				hdr.Size += s.Length

</p>

<h2 id="Blocks">Blocks</h2>

<p>
A <i>block</i> is a possibly empty sequence of declarations and statements
within matching brace brackets.
</p>

<pre class="ebnf">
Block = "{" StatementList "}" .
StatementList = { Statement ";" } .
</pre>

<p>
In addition to explicit blocks in the source code, there are implicit blocks:
</p>

<ol>

// A subsequent deadcode pass is needed to actually remove the copies.
func copyelim(f *Func) {
	phielim(f)

	// loop of copyelimValue(v) process has been done in phielim() pass.
	// Update block control values.
	for _, b := range f.Blocks {
		for i, v := range b.ControlValues() {
			if v.Op == OpCopy {
				b.ReplaceControl(i, v.Args[0])
			}
		}
	}

	// Update named values.
	for _, name := range f.Names {

			base.Fatalf("in %s, badly placed LoweredGetClosurePtr: %v %v", v.Block.Func.Name, v.Block, v)
		}
	}
}

// CheckArgReg ensures that v is in the function's entry block.
func CheckArgReg(v *ssa.Value) {
	entry := v.Block.Func.Entry
	if entry != v.Block {
		base.Fatalf("in %s, badly placed ArgIReg or ArgFReg: %v %v", v.Block.Func.Name, v.Block, v)
	}
}

func AddrAuto(a *obj.Addr, v *ssa.Value) {